Energon Scorponok has an awesome fortress mode. You basically transform him to scorpion mode, split the head/shoulders and swing them to the sides, starightening the claws to sit parallel with them. rotate the tail straight up the move it back and down, and do whatever you want with the legs. It makes a great building/base/fortress for minicons.

Arm Megatron is also great for mini-con/micromasters, just radomly extend and unfold limbs and panels and it's a little gun station thing.